Does anybody have a contact address/number for the ESOL exam centre dealing with Lesvos?
I tried to find the information on the Cambridge website but could only find a (long) list of bodies throughout Greece, the list was not geographically explicit.

I haven't lived in Greece for a few years but when I was there, the administration of Cambridge ESOL wasn't organised geographically like in some countries. At first the British Council had a total monopoly, but then some other centres started to open. So in effect you can live in one place but choose on an exam centre. Most of these are closed centres though, meaning they are run by schools and can only enter their own students as candidates. You could look up eurognosi and see if they have a school in Lesvos. This is a chain of schools and also a closed exam centre.